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The BA.2 Omicron subvariant: What you need to know – New Zealand Herald

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There were tn Covid-related deaths in New Zealand on Thursday, and 19,566 new cases.
Video / NZ Herald

By RNZ

The BA.2 subvariant of Omicron has quickly become the dominant strain of Covid-19 in New Zealand. What is it and what impact will it have on the current outbreak? RNZ is here to clear it all up.

Over time viruses change and mutate, creating new variants and subvariants. As we know, there are a number of variants of Covid-19, each given their own letter of the Greek alphabet like Beta, Delta and Omicron. BA.2 is one of several subvariants of the Omicron variant of Covid-19 – not quite unique enough to be given its own letter, though whether it should still have one is debatable.

When you think about Omicron, until now it was likely you’re thinking about BA.1, which was dominant in most Omicron outbreaks until recently. BA.1 and BA.2 have differences in genetic sequence, including amino acids and proteins.

BA.2 was first detected in November 2021, around the same time as BA.1 but by mid-March 2022, BA.2 was rapidly gaining momentum around the world.

First found in New Zealand in late-January when a number of border workers and close contacts tested positive, as of mid-March, nearly 80 per cent of recent cases that had undergone genomic sequencing here were found to be the BA.2 subvariant.

Though with rapid antigen tests now the dominant form of testing in New Zealand, genomic sequencing is less common than it once was and so it is impossible to know just how widespread a variant is at any one time.

It’s highly unlikely you will know whether you’ve tested positive for BA.1 or BA.2 if you’ve tested positive for Covid-19.

Director general of health Dr Ashley Bloomfield says the prevalence of BA.2 was part of the reason why case numbers in Auckland during the peak of the Omicron outbreak were higher than modelling predicted.

Health officials in England reported the vaccine was similar in effectiveness against symptomatic disease for both BA.1 and BA.2. Photo / Michael Craig

What does this mean for the Omicron outbreak?

While it may prolong the Omicron surge, it’s unlikely the rise in BA.2 cases would result in a large second wave as some countries are dealing with, Otago University virologist Dr Jemma Geoghegan told Morning Report.

In fact, she says, seeing a rise in BA.2 at the same time as BA.1 is the best possible scenario and having this happen at the end of summer and among a highly vaccinated population was an advantage too.

Bloomfield says if the majority of cases in New Zealand’s outbreak were BA.2 it could act in the country’s favour.

He says some places such as New South Wales, the UK and particularly Scotland – were seeing second outbreaks with the BA.2 subvariant, having already had BA.1 subvariant outbreaks.

“Even those jurisdictions that had an initial quite big Omicron outbreak are getting a second one, that seems to be associated with the BA.2 subvariant.”

If most of New Zealand’s Omicron cases are already the BA.2 subvariant, Bloomfield says there is a chance “we will miss that second big peak again that other countries are seeing”.

That’s what has happened in Denmark, which saw a rise in BA.2 during its first Omicron wave.

Is it more transmissible?

It’s estimated BA.2 is up to 40 per cent more transmissible than the already highly transmissible BA.1.

A study of 8,500 households and 18,000 individuals conducted by Denmark’s Statens Serum Institut (SSI) found that BA.2 was “substantially” more transmissible than BA.1, though it’s important to note this has not yet been peer reviewed.

A separate UK study also found higher transmissibility for BA.2 compared to BA.1.

Data is still limited but the World Health Organisation says people have been reinfected with BA.2 after having had an infection of BA.1.

“Data suggests that antibodies from past BA.1 infection does give you some protection against BA.2, although clearly reinfections can happen, they’re probably more rare,” Geoghegan says.

It's highly unlikely you will know whether you've tested positive for BA.1 or BA.2 if you've tested positive for Covid-19. Photo / Alex Burton
It’s highly unlikely you will know whether you’ve tested positive for BA.1 or BA.2 if you’ve tested positive for Covid-19. Photo / Alex Burton

Is it more severe?

Bloomfield says while BA.2 is more transmissible, there is currently no evidence to suggest it is more or less severe.

A risk assessment report from Denmark’s SSI in late-February found there wasn’t an increased risk of hospital admission associated with BA.2 compared to BA.1. And that’s what researchers in England found too.

How effective are vaccines against BA.2 ?

Vaccines appear to effectively shield people against the highly transmissible BA.2, Geoghegan says.

“The real-world data suggests there’s no difference in disease severity between the two variants and the vaccine and boosters appear to be providing really good protection against both subvariants as well.”

Health officials in England reported the vaccine was similar in effectiveness against symptomatic disease for both BA.1 and BA.2.

Pfizer boss Albert Bourla told CBS the company is currently trying to make a vaccine that would protect against all variants, and last up to a year.

Both Pfizer and Moderna think a fourth dose of their Covid-19 vaccines – a second booster shot – is necessary as the protection from earlier doses wanes.

The BA.2 subvariant has quickly become the dominant strain of Covid-19 in NZ. Photo / Nik Dirga, RNZ
The BA.2 subvariant has quickly become the dominant strain of Covid-19 in NZ. Photo / Nik Dirga, RNZ

How is a new variant found?

PCR testing continues to be used in hospital settings and at the border as part of New Zealand’s surveillance regime, allowing officials to detect new variants in the country – this surveillance testing is how officials know BA.2 is on the rise here.

Prime Minister Jacinda Ardern wants New Zealand to become “really sufficient” at surveillance at the border, “gold standard,” she says.

Auckland University’s Dr David Welch says the border reopening has increased the need for better testing for the virus to guard against new variants.

Can we expect more variants (or subvariants) in the future?

New variants of Covid-19 pop up all of the time and have done since the beginning of the outbreak, whether of not they become a ‘variant of concern’ is decided by the World Health Organisation. The subvariants of Omicron are currently being monitored by WHO.

“With less stringent border restrictions we expect to see new lineages of viral genomes – genomics enables us to watch these closely,” the Institute of Environmental Science and Research’s principal scientist and genomics lead Professor Mike Bunce and lead bioinformatics and genomics, Dr Joep de Ligt say in a joint statement.

“Hospital cases are a priority for genome sequencing. The genomic surveillance plan also calls for multiple samples to be taken from patients that have a prolonged infection with Covid-19. The risk here is that the virus, if not ‘cleared’, can accumulate mutations; we can monitor this by taking samples over time and seeing if key parts of the virus (such as the spike protein) are changing,” they say.

“New variants can also emerge in long-haul (long Covid) patients, and there is an increasing awareness of this on the international stage.”

Dr Welch says MIQ gave New Zealand a “real time buffer and that time buffer has allowed us to plan to prepare”.

“If we can detect something at the border then you know it would still have to grow inside New Zealand and spread, so spotting at the border rather than once it’s already spread widely, could give us a … two or four weeks heads-up.”

– Additional reporting from BBC

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Some in B.C. cross U.S. border for their next COVID-19 vaccine – Global News

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Global News Hour at 6 BC

There is evidence of the lengths some British Columbians will go to get a second booster dose of the COVID-19 vaccine — crossing the border to Point Roberts, WA for a shot. The movement comes thanks to the different approach to the fourth shot south of the border. Catherine Urquhart reports.

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Unknown hepatitis in children: Will it become a pandemic too? – CGTN

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The number of cases of a mysterious acute hepatitis in children continues to increase worldwide, with most cases occurring in Europe. As of May 10, 348 suspected cases had been reported in at least 20 countries. Information and data have pointed to an adenovirus called adenovirus-41 (HAdV-41) as the possible culprit. Does it have anything to do with COVID? Will it become a pandemic? How do we protect ourselves from it?

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Study tracks hospital readmission risk for COVID-19 patients in Alberta, Ontario – CBC.ca

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A new study offers a closer look at possible factors that may lead to some hospitalized COVID-19 patients being readmitted within a month of discharge.

At roughly nine per cent, researchers say the readmission rate is similar to that seen for other ailments, but socio-economic factors and sex seem to play a bigger role in predicting which patients are most likely to suffer a downturn when sent home.

Research published Monday in the Canadian Medical Association Journal looked at 46,412 adults hospitalized for COVID-19 in Alberta and Ontario during the first part of the pandemic. About 18 per cent — 8,496 patients — died in hospital between January 2020 and October 2021, which was higher than the norm for other respiratory tract infections.

Among those sent home, about nine per cent — 2,759 patients — returned to hospital within 30 days of leaving, while two per cent — 712 patients — died. The deaths include patients who returned to hospital.

The combined rate of readmission or death was similar in each province, at 9.9 per cent or 783 patients in Alberta, and 10.6 per cent or 2,390 patients in Ontario.

For those wondering if the patients were discharged too soon, the report found most spent less than a month in hospital and patients who stayed longer were actually readmitted at a slightly higher rate.

“We initially wondered, ‘Were people being sent home too early?’ … and there was no association between length of stay in hospital and readmission rates, which is reassuring,” co-author Dr. Finlay McAlister, a professor of general internal medicine at the University of Alberta, said from Edmonton.

“So it looked like clinicians were identifying the right patients to send home.”

Examining the peaks

Craig Jenne, an associate professor of microbiology, immunology and infectious diseases at the University of Calgary who was not involved in the research, said the study suggests that the health-care system was able to withstand the pressures of the pandemic. 

“We’ve heard a lot about how severe this disease can be and there was always a little bit of fear that, because of health-care capacity, that people were perhaps rushed out of the system,” Jenne said. “There was a significant increase in loss of life but this wasn’t due to system processing of patients.

“Care was not sacrificed despite the really unprecedented pressure put on staff and systems during the peaks of those early waves.” 

The study also provides important insight on the power of vaccines in preventing severe outcomes, Jenne said.

Of all the patients admitted with COVID-19 in both provinces, 91 per cent in Alberta and 95 per cent in Ontario were unvaccinated, the study found.

The report found readmitted patients tended to be male, older, and have multiple comorbidities and previous hospital visits and admissions. They were also more likely to be discharged with home care or to a long-term care facility.

McAlister also found socio-economic status was a factor, noting that hospitals traditionally use a scoring system called LACE to predict outcomes by looking at length of stay, age, comorbidities and past emergency room visits, but “that wasn’t as good a predictor for post-COVID patients.”

“Including things like socio-economic status, male sex and where they were actually being discharged to were also big influences. It comes back to the whole message that we’re seeing over and over with COVID: that socio-economic deprivation seems to be even more important for COVID than for other medical conditions.”

McAlister said knowing this could help transition co-ordinators and family doctors decide which patients need extra help when they leave the hospital.

‘Deprivation’ indicators

On its own, LACE had only a modest ability to predict readmission or death but adding variables including the patient’s neighbourhood and sex improved accuracy by 12 per cent, adds supporting co-author Dr. Amol Verma, an internal medicine physician at St. Michael’s Hospital in Toronto.

The study did not tease out how much socio-economic status itself was a factor, but did look at postal codes associated with so-called “deprivation” indicators like lower education and income among residents.

Readmission was about the same regardless of neighbourhood, but patients from postal codes that scored high on the deprivation index were more likely to be admitted for COVID-19 to begin with, notes Verma.

Verma adds that relying on postal codes does have limitations in assessing socio-economic status since urban postal codes can have wide variation in their demographic. He also notes the study did not include patients without a postal code.

McAlister said about half of the patients returned because of breathing difficulties, which is the most common diagnosis for readmissions of any type.

He suspected many of those problems would have been difficult to prevent, suggesting “it may just be progression of the underlying disease.”

Looking at readmissions is just the tip of the iceberg.-Dr. Finlay McAlister-Dr. Finlay McAlister

It’s clear, however, that many people who appear to survive COVID are not able to fully put the illness behind them, he added.

“Looking at readmissions is just the tip of the iceberg. There’s some data from the [World Health Organization] that maybe half to two-thirds of individuals who have had COVID severe enough to be hospitalized end up with lung problems or heart problems afterwards, if you do detailed enough testing,” he said.

“If you give patients quality of life scores and symptom questionnaires, they’re reporting much more levels of disability than we’re picking up in analyses of hospitalizations or emergency room visits.”

The research period pre-dates the Omicron surge that appeared in late 2021 but McAlister said there’s no reason to suspect much difference among today’s patients.

He said that while Omicron outcomes have been shown to be less severe than the Delta variant, they are comparable to the wild type of the novel coronavirus that started the pandemic.

“If you’re unvaccinated and you catch Omicron it’s still not a walk in the park,” he said.

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